PORSCHE TECH­NI­CAL TOP­ICS

I was chat­ting to Steve Mchale at JZM in Kings Langley, Hert­ford­shire, a few weeks ago, the oc­ca­sion be­ing the cof­fee morn­ing he and his en­thu­si­as­tic staff had or­gan­ised – and which brought out no fewer than 250 peo­ple, in what must have been at least 200 Porsches of pretty much ev­ery shape and size. It was quite a sight, es­pe­cially for a Sun­day, with vir­tu­ally the en­tire in­dus­trial es­tate full of Stuttgart's finest.

Some­how or other we got on to the sub­ject of the rear­win­dow washer in Cayennes – I al­ways like to glean some tech­ni­cal nugget or other from Porsche peo­ple with Steve’s long ex­pe­ri­ence – and more specif­i­cally what to do if, or more likely when, it ever stops work­ing.

‘Stop us­ing it!’ was Steve’s char­ac­ter­is­ti­cally sim­ple, pithy ad­vice. ‘And get it fixed.’ That sounds pretty ob­vi­ous, of course, but there is a nat­u­ral ten­dency among we hu­mans to keep jab­bing at any sud­denly un­re­spon­sive switch or con­trol in the usu­ally vain hope that the prob­lem will mirac­u­lously some­how cure it­self. I did ex­actly the same my­self last week, when the driver’s win­dow of my Vito van wouldn’t re­li­ably roll back up again, clearly in­di­cat­ing some kind of elec­tri­cal rather than purely me­chan­i­cal is­sue. (It’s now work­ing again, as it hap­pens, but for how long?)

It may be sim­ply that the washer sys­tem’s fluid reser­voir is empty, which is easy enough to check and rec­tify. What of­ten hap­pens, how­ever, is that the jets block up – with ei­ther plain, old-fash­ioned dirt or, if you live in an area with so-called ‘hard’ wa­ter, with cal­cium de­posits. And that is Very Bad News. Be­cause the pump, bless it, delivers at such a rel­a­tively high pres­sure that some­thing else within the sys­tem has to give. And usu­ally it’s where the plas­tic pipe car­ry­ing the fluid from the front of the car to the rear meets an ‘L’-shaped con­nec­tor deep within the dash­board.

Once that hap­pens, says Steve, op­er­at­ing the switch squirts a hefty dose of liq­uid all over the mas­sively com­pli­cated ad­ja­cent wiring (and re­mem­ber that most screen­wash an­tifreeze ad­di­tives are also flammable) from where, in the full­ness of time, it usu­ally ends up in­side the ECU that con­trols many of the car’s ‘body’ sys­tems, such as the door locks, the win­dow and seat mo­tors, and not least the cen­tral-lock­ing. You re­ally couldn’t make it up if you tried, could you?

Re­pair is a time-con­sum­ing and thus costly process, adds Steve, re­quir­ing the strip­ping out of ev­ery last cen­time­tre of cor­roded ca­ble, and its re­place­ment us­ing the cor­rect spe­cialised con­nec­tors (which, need­less to say, JZM buys in from the rel­e­vant sup­plier; noth­ing less than the best will do). In­deed, the cost can be a sig­nif­i­cant pro­por­tion of what an older Cayenne might now be worth, and while that isn’t nec­es­sar­ily a de­ter­rent – if you are in that deep you of­ten have no choice but to keep go­ing; look at the hostages to for­tune that many 996 and 997 own­ers have be­come – it surely has to hurt. Fore­warned is al­ways fore­armed.

JZM’S Sun­day cof­fee morn­ing on 11th June was at­tended by more than 250 en­thu­si­asts, in per­haps as many as 200 cars. Next event is on 1st Oc­to­ber, of­fer­ing an­other chance to see the com­pany’s lat­est stock, tour the work­shop and, if you are very lucky, bend Steve Mchale’s ear with tech­ni­cal queries...